This invention relates generally to improvements in a coupler for use in a fluid circuit, and more particularly to a dust-sealing assembly that precludes blockage between relatively movable parts that would adversely affect operation of the coupling. The present dust-sealing assembly is adapted for particular use with a hydraulic coupler that is disclosed and claimed in U.S. Pat. No. 4,074,698 issued Feb. 21, 1978, the disclosure of which is incorporated by reference. In this hydraulic coupler, a compression spring is located around each of the sleeve members, and is disposed in the space between the coupler body member and the nipple-releasing means. The compression spring tends to hold the body member away from the nipple-releasing means that is fixed to the mounting plate. Because the space between the body member and nipple-releasing means is open and the spring is exposed, foreign material such as dirt, mud, gravel, vegetation and the like, can enter this space and possibly cause blockage of the spring and of the relative movement between the body member and nipple-releasing means against spring loading, and thereby adversely affect coupler operation.